Discrete lot powder management for additive manufacturing

ABSTRACT

A method of additive manufacturing includes supplying additive manufacturing powder to a build area of an additive manufacturing machine. The method includes fusing a portion of the powder to form a part, and removing a non-fused portion of the powder from the build area into a removable vessel for storing non-fused powder after building a part. The method can include supplying additive manufacturing powder to a build area, fusing a portion of the powder, and removing a non-fused portion of the powder all on a single discrete lot of additive manufacturing powder without mixing lots.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of U.S. patent application Ser. No. 15/850,330filed Dec. 21, 2017, which is incorporated by reference herein in itsentirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present disclosure relates to additive manufacturing, and moreparticularly to powder handling for additive manufacturing.

2. Description of Related Art

Some additive manufacturing machines use laser sintering to fusemetallic powder. As a part is printed or grown in a fabrication pistonor build area, much of the powder in the fabrication piston or buildarea remains non-fused after the part is finished. Some additivemanufacturing machines include onboard sieving/recycling units thatcollect and hold non-fused powder after a build. The sieving/recyclingunits then sieve the powder in the machine and return the sieved powderto the feed piston area using tubing and turbines to transport thepowder so the powder can be fed to the fabrication piston or build areafor manufacturing the next part. These systems are referred to as powderrecycling systems, and they reduce the amount of new powder that has tobe added to the system for subsequent builds. In manufacturing aerospaceparts, however, the high manufacturing standards require powder lottraceability. The traditional powder recycling systems are not conduciveto powder lot traceability since powder from multiple powder lots canget mixed together during the recycling process.

The conventional techniques have been considered satisfactory for theirintended purpose. However, there is an ever present need for improvedadditive manufacturing techniques. This disclosure provides a solutionfor this need.

SUMMARY OF THE INVENTION

A method of additive manufacturing includes supplying additivemanufacturing powder to a build area of an additive manufacturingmachine. The method includes fusing a portion of the powder to form apart, and removing a non-fused portion of the powder from the build areainto a removable vessel for storing non-fused powder after building apart.

The method can include supplying additive manufacturing powder to abuild area, fusing a portion of the powder, and removing a non-fusedportion of the powder all on a single discrete lot of additivemanufacturing powder without mixing lots.

Removing a non-fused portion of the powder from the build area into aremovable vessel can include transporting the non-fused portion of thepowder into the removable vessel under an inert atmosphere. The inertatmosphere can include at least one of a vacuum, a noble gas, and/ornitrogen gas. The method can include sealing the non-fused portion ofthe powder within the vessel under the inert atmosphere. The method caninclude inserting a powder sampling probe into the vessel to retrieve asample of the non-fused powder without compromising the inert atmospherewithin the vessel. The method can include removing the non-fused powderfrom the vessel within an inert atmosphere, sieving the non-fused powderwithin the inert atmosphere, and returning the non-fused powder into thevessel and sealing the vessel under the inert atmosphere.

The method can include supplying the unused portion of powder from thevessel to the build area of an additive manufacturing machine, andadditively manufacturing a second part exclusively from the powder fromthe vessel. Additively manufacturing the second part can include formingthe second part entirely with powder from the vessel, wherein the vesselhas a capacity of 8 gallons (30.3 Liters).

The method can include heating the vessel and the non-fused powder todrive moisture and/or oxygen gas from the non-fused powder. The methodcan include pulling a vacuum on the removable vessel, either alone orduring heating to pull off oxygen and/or moisture from the non-fusedportion of the powder, and backfilling the removable vessel to ambientpressure with inert gas. The method can include rolling and/or tumblingthe vessel and the non-fused powder therein to increase homogeneity inthe non-fused powder. The method can include providing a means forcreating and maintaining an inert atmosphere within the sealable vesselduring filling of the sealable vessel during operation of the additivemanufacturing machine.

A method of retrofitting an additive manufacturing machine includesdisconnecting a powder sieve of a recycling system in an additivemanufacturing machine and connecting and sealing a sealable vessel tothe additive manufacturing machine to receive powder from the additivemanufacturing machine in lieu of the sieve.

Disconnecting the powder sieve can include disconnecting the powdersieve from a powder conveyance conduit, and connecting the sealablevessel can include connecting the sealable vessel to the powderconveyance conduit. Connecting the sealable vessel can include seatingthe sealable vessel in a lift to support the sealable vessel withoutloading the powder conveyance conduit with weight from the sealablevessel.

An additive manufacturing machine includes a build area for powderfusion additive manufacturing. A powder conveyance conduit isoperatively connected to the build area for conveying non-fused powderaway from the build area after a build. A vessel is sealed to the powderconveyance conduit for receiving the non-fused powder.

These and other features of the systems and methods of the subjectdisclosure will become more readily apparent to those skilled in the artfrom the following detailed description of the preferred embodimentstaken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those skilled in the art to which the subject disclosureappertains will readily understand how to make and use the devices andmethods of the subject disclosure without undue experimentation,preferred embodiments thereof will be described in detail herein belowwith reference to certain figures, wherein:

FIG. 1 is a schematic view of an exemplary embodiment of an additivemanufacturing machine constructed in accordance with the presentdisclosure, showing the device with an operational powder recyclingsystem;

FIG. 2 is a schematic view of the additive manufacturing machine of FIG.1, showing the machine after a retrofitting with a sealable vessel; and

FIG. 3 is a schematic view of the machine of FIG. 1, showing thesealable vessel with non-fused powder sealed therein in an inertatmosphere.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to the drawings wherein like referencenumerals identify similar structural features or aspects of the subjectdisclosure. For purposes of explanation and illustration, and notlimitation, a partial view of an exemplary embodiment of an additivemanufacturing machine in accordance with the disclosure is shown in FIG.1 and is designated generally by reference character 100. Otherembodiments of additive manufacturing machines in accordance with thedisclosure, or aspects thereof, are provided in FIGS. 2-3, as will bedescribed. The systems and methods described herein can be used toprovide discrete powder lot management for additive manufacturing, e.g.,for ensuring aerospace standards are maintained in materials used toadditively manufacture aerospace components.

The additive manufacturing machine 100 includes a build area 102 forpowder fusion additive manufacturing, e.g., by laser 104 fusing powderin the build area 102 to form a part or component 106. A powder supply105, which can be a hopper, feed piston, or the like, supplies thepowder to the build area 102 through conduit 107 during the build. Afterthe build is complete, the build area 102 contains both fused powder,which is incorporated in the component 106, as well as non-fused powder108. A powder conveyance conduit 110 is operatively connected to thebuild area 102 for conveying the non-fused powder 108 away from thebuild area 102 after a build, as indicated by the large arrow in conduit110 in FIG. 1. The conduit 110 conveys the non-fused powder 108 througha sieve 112 to remove any anomalous material from the non-fused powder.A turbine 114 and conveyance conduit 116 convey the sieved powder backto the powder supply 105. This configuration allows for recycling powderfrom one build to be used in subsequent builds, but mixes the powderfrom one lot with powder from other lots over time as new powder lotsare added to replace the fused powder leaving the machine as completedbuilds.

With reference now to FIG. 2, a method of retrofitting the additivemanufacturing machine 100 (e.g., starting with a ProX300 additivemanufacturing machine available from 3D Systems, Inc. of Rock Hill,S.C.) includes disconnecting the powder sieve 112 (shown in FIG. 1) ofthe recycling system in an additive manufacturing machine 100 andconnecting and sealing a sealable, removable vessel 118 to the additivemanufacturing machine 100 to receive powder from the additivemanufacturing machine 100 in lieu of the sieve 112. Disconnecting thepowder sieve 112 includes disconnecting the powder sieve 112 from thepowder conveyance conduits 110 and 116, and connecting the sealablevessel 118 includes connecting the sealable vessel 118 to the powderconveyance conduit 110, e.g., using tri-clamp hardware 119 and valve124. Seating the sealable vessel 118 in a rolling scissor lift 120provides support for sealing the sealable vessel 118 to conduit 110without loading the powder conveyance conduit 110 with weight from thesealable vessel 118 and powder therein, e.g., a combined weight of 350lbs (158.8 kg) or more. A bladder lift or any other suitable type oflift can be issued in addition to or in lieu of scissor lift 120. Avalve 122 in the conduit 110 and a valve 124 in sealable vessel 118allow for sealing engagement and disengagement of vessel 118 with theconduit 110 without compromising the inert atmosphere within either,e.g., one or both of valves 122 and 124 can include an airlock toeliminate non-controlled atmosphere between valves 122 and 124 fromentering the system when connecting the vessel 118 to the conduit 110.As shown in FIG. 2, the vessel 118 is sealed to the powder conveyanceconduit 110 and the valves 122 and 124 are opened for receiving thenon-fused powder into the vessel 118. As shown in FIG. 3, the valves 122and 124 are both closed to allow removal of the vessel 118 and thenon-fused powder therein from the conduit 110 without exposing thenon-fused powder to an uncontrolled atmosphere.

In the configuration shown in FIG. 2, additive manufacturing can beperformed with a single discrete lot of powder without mixing powderlots, and the unused or non-fused powder 108 can be saved in the vessel118, which can be labeled for use in a subsequent build from the samesingle discrete powder lot. This method includes supplying additivemanufacturing powder to the build area 102 from the supply 105 during abuild. A portion of the powder is fused to form a part 106, and thenon-fused portion of the powder is removed from the build area into aremovable vessel 118 for storing the non-fused powder after building thepart 106. Removing a non-fused portion 108 of the powder from the buildarea 102 into the removable vessel 118 includes transporting thenon-fused portion of the powder into the removable vessel 118 under aninert atmosphere such as a vacuum, a noble gas, and/or nitrogen gas. Thenon-fused portion 108 of the powder can be sealed by valve 124 withinthe vessel 118 under the inert atmosphere.

As shown in FIG. 3, a powder sampling probe 126 can be inserted into thevessel 118 to retrieve a sample of the non-fused powder 108 withoutcompromising the inert atmosphere within the vessel 118. For example, ifthe inert atmosphere includes a heavy noble gas like Argon, the vessel118 can be opened from the top, the probe 126 can be inserted from aboveinto the vessel 118, and the negative buoyancy of Argon will keep theinert atmosphere covering the powder inside vessel 118 during while thesample is taken. Once the non-fused powder 108 is sealed in the vessel118, additional processes can be performed off-line from the machine100. The non-fused powder 108 can be removed from the vessel 118 withinan inert atmosphere, and the powder can be sieved within the inertatmosphere, as indicated by box 128 in FIG. 3. Thereafter, the sievedpowder can be returned into the vessel 118 and sealed in the vesselunder the inert atmosphere. The vessel 118 can be used for storage ofthe powder until it is needed for another build, as indicated by box 130in FIG. 3. Moisture and/or oxygen gas can be driven from the non-fusedpowder by heating the vessel 118 with the powder 180 therein to asuitable temperature such as 350° F. (176.7° C.), as indicated by box132 in FIG. 3. For example, the method can include pulling a vacuum onthe removable vessel 118, either alone or during heating to pull offoxygen and/or moisture from the non-fused portion of the powder, andbackfilling the removable vessel 118 to ambient pressure with inert gas.It is also contemplated that the vessel 118 and powder sealed thereincan be rolled and/or tumbled to increase homogeneity in the non-fusedpowder 108, as indicated by box 134 in FIG. 3. The vessel 118 can beremoved from the scissor lift 120 and transported as needed for storageand/or processing using a motorized lift and transport device.

As indicated by box 136 in FIG. 3, the method includes supplying theunused or non-fused portion of powder 108 from the vessel 118 to thebuild area of an additive manufacturing machine, e.g., by emptying thevessel 118 into supply 105 under sealed conditions by way of valves 124and 138, and additively manufacturing a subsequent part exclusively fromthe powder from the vessel 118. The vessel can be large enough, e.g, 8gallons (30.3 Liters), to hold enough powder for an entire build, e.g.,where the part being built weighs 300 lbs (136.1 kg) or more whenfinished if nickel is used, or roughly half that weight if aluminum isused, or the appropriate weight if any other suitable metal is used.

There are many potential advantages to powder lot management systems andmethods as disclosed herein. Powder lot integrity can be maintained withgreater ease than in traditional systems. Collecting samples foroxidation testing and particle size distribution and morphology andsatellites is facilitated relative to in traditional systems. Using thevessels disclosed herein together with scissor lifts and motorized liftsor the like allows safe and easy movement of powder by a single person.Introduction of unwanted contaminants into the powder can be avoided bykeeping the powder under controlled atmospheric conditions at all times.Complications and delays related to use of recycling systems intraditional additive manufacturing machines can be eliminated becausesieving can be performed off line while the machine continues the nextbuild. This reduced maintenance and down time for the additivemanufacturing machine, allowing increased production and reduced cost.

The methods and systems of the present disclosure, as described aboveand shown in the drawings, provide for improved powder lot managementwith superior properties including the ability to reuse additivemanufacturing powder without mixing powder from multiple lots. While theapparatus and methods of the subject disclosure have been shown anddescribed with reference to preferred embodiments, those skilled in theart will readily appreciate that changes and/or modifications may bemade thereto without departing from the scope of the subject disclosure.

What is claimed is:
 1. A method of retrofitting an additivemanufacturing machine comprising: disconnecting a powder sieve of arecycling system in an additive manufacturing machine; and connectingand sealing a sealable vessel to the additive manufacturing machine toreceive powder from the additive manufacturing machine in lieu of thesieve.
 2. The method as recited in claim 1, wherein disconnecting thepowder sieve includes disconnecting the powder sieve from a powderconveyance conduit, and wherein connecting the sealable vessel includesconnecting the sealable vessel to the powder conveyance conduit.
 3. Themethod as recited in claim 1, wherein connecting the sealable vesselincludes seating the sealable vessel in a lift to support the sealablevessel without loading the powder conveyance conduit with weight fromthe sealable vessel.
 4. The method as recited in claim 1, furthercomprising providing a means for creating and maintaining an inertatmosphere within the sealable vessel during filling of the sealablevessel during operation of the additive manufacturing machine.
 5. Anadditive manufacturing machine comprising: a build area for powderfusion additive manufacturing; a powder conveyance conduit operativelyconnected to the build area for conveying non-fused powder away from thebuild area after a build; and a vessel sealed to the powder conveyanceconduit for receiving the non-fused powder.
 6. The additivemanufacturing machine as recited in claim 5, wherein the vessel has acapacity of 8 gallons (30.3 Liters).